Fuel injection system



Oct. 7, 1952 R. A. LASLEY 2,612,340

FUEL INJECTION SYSTEM Filed May 15, 1948 2 Sl-IEETSSHEET 1 IN V EN TOR.

Oct. 7, 1952 R. A. LASLEY FUEL INJECTION SYSTEM 2 SHEETSSHEET 2 Filed May 15, 1948 a w E /222w 4/ diZor/z Patented Oct. 7, 1952 UNITED srAyr-ss our "OFFICE;

uE -iNJEono SYSTEM Robert At Lasley,

Chicago, 111. assignor, byinesne assignments, jflaLQllifiaG. Si nmons, .Chi cag9, Ill;

Applications/[axis 1948;SerialNo.'26,-85'0 I 'ao aims. (01. 103-41.)

This invention relatesto fuel injectiomsystems for-compression-ignition or diesel engines, and

more particularly; to fuel injection systems of;

the typev including a hydraulically or p' ressure operated; injector, connected through afuel line to-thehigh pressure outlet-oi a pump which is to preventreturn of fuel from the fuelline to the pump between injections, and difficulties have been encounteredwith secondary injection caused by the pressure Wavethat isset up in the sealed. fuel. line. upon closure, of the. injector nozzle. It

. has heretofore been proposed tominimize or elim:

inate. such secondary injection or dribble at the, fuel nozzle by designing the discharge valves to provide. a. predetermined amount of retraction that. is, withdrawal, of fuel from the fuel. lineduring closure of the, discharge valve...

The amount of fuelto be withdrawn from the, fuel line-to prevent secondary injection without, interferingwith the. accuracy ofsuhsequent pri-. mary, injecti ns, of coursed p nds n u us .factors including primarilyv the, amount of fuel injected, which is a function of the load-and speed of, the engine. If too,much retraction is provided, the .fuel line may be partially emptied-,7

and consequently insufficient fuel may be supplied to the injector for the next in ction, par ticularly at light loads while if too little retraction is providedsecondary injection may not beprevented. Consequently, it has been the practice to design the d scharge valvesto. provide the minimum amount of retraction necessaryfor satisfactory injection atnormal loads and speeds with the result that the rangeof loads and speeds that the, engine may handle without encountering objectionable injection characteristics has been severely limited. Something is yet to be desired, therefore, in injection systems of this character, and it is a further: object of this. invention to provide an injection system wherein the retraction, 1-. e., the amount of fuel withdrawn from the fuel line between; injections, is automatically varied" to provide proper injection overa wide. range of loads and speeds.

character whichare capable of In carrying outr the invention in' one'form a fuel injection system is providedlhal in zdischargeg valve means; which incorporate: means; for aut 1s matically varying; the amount of fllel withdra y fromthe fuel line in accordance withthe amount of' fuel supplied byE-the pump during injection): More particularly,, the discharge I valve m, may include aflpair of valves each (if-which cludes retraction means, one-sofa the: Whose-118 adaptedto. open: under a. lesser: pressurerthan the other:

' Fora more complete understanding ofzthe vention, reference should now be had toythe;

drawings, in which:- 'Figl illustratesdiagrammatically a fuel lineartion system of'thetypeinwhich the present:-in. vention is embodied;

Fig. 2 is a vertical sectional'view 'of'o-neifor m of pump and discharge valve meansiwhichimays be employedrinqsystems embodying the ;inven-tion Fig. 3 isa, similar-fragmentary; sectional aviewg on a largerscale; showing-the: discharge valve; means of'Fig; 2;-; I I Fig. 4 is a similar fragmentary sectionalview;

of anotherform of discharge valve means emebodying the-invention;- r

Fig. 5; isa similar fragmentary; sectional view illustrating still? anotnenf rmof discharge-valve? means; and

Elisa. 6151 est ,tionalewa nlo iestho in B-B.of Fig. 5;.- j l In o mer to. dra in s th n eiiea s: sh wnr sz' mb. .d edmin ectio s s m? c mp i as; n i 1 fu l wisp-Tm? '15 c c d u h; atop-Zia. i 3-" j i tahle r el nisc on pm Z- Th n ect iiiis o fs e. ;type well known; in the art, which is; commonly.- identified 5 as of the closed, differential; hydraulicfoperated. type, and; includes a spring loaded differential needle valve, (notv shown). adapted, to be opened .by,,fue l. pressurehcreated by the fuel pump-and: toIb'e-closed by the. spring when. the fuel pressure is...relieved, So; that. the, fuel, during- .the interyaL when. the needle valve is: open, will be. forced, through suitable. ori n he iniectorrioz le 3. into. the, opio s on, amb rof theensine- The uol pu p. "w ich toFig. 2 the fuel pump this shown as comprising a suitable longitudinally body- I4" formed to provide 'a pale.

bored pump 3 mary fuel chamber l5 to which fuel is supplied through a suitable inlet fitting l6. Disposed within the pump body I4 is a cylinder barrel I! having an inlet port 16 and a spill port l9 communicating with the fuel chamber l5. The cylinder barrel I7 is adapted to contain a piston 26 which is provided adjacent its upper end with a longitudinally extending slot 2i which communicates with an inclined or helically disposed slot 22 adapted to coo erate with the spill port I9 in a manner well understood in the art and which will be briefly described hereinafter.

As shown, the piston is provided adjacent its lower end with a suitable head or collar 23 for receiving a spring retainer 24 adapted to be engaged by the lower end of a spring 25, the upper end of which bears against a spring retaining washer or collar 26 arranged to engage a suitable shoulder 21 formed in the pump body l4.- The'spring serves to urge the piston 20 in a downward direction, as viewed in Fig. 2, and a suitable spring cup 28 slidably disposed within the lower portion of the pump body 14 so as to be enga ed by the collar 23 on the lower end of the piston 20 is adapted to be enga ed by a suitable cam follower 29 which cooperates with the usual engine driven cam 30 toetlect actuation of the piston 20.

'Aswill be understood by those skilled in the art, the pump I2 is of the constant stroke type and the piston 20 is axially adjustable in the cylinder barrel I! to vary the amount of high pressure fuel delivered at each stroke of the pump. Briefly. when thepiston is in its lowermost position the pressure chamber 20a within the cylinder barrel above the piston will be filled with fuel by suction through the inlet port I 8 and 'the s ill port I9. As the piston begins its upward travel the fuel in the chamber 2911 will be plac d under pressure and as soon as the upper ed e of the piston mo es beyond the inlet port l8, high pressure will be developed so as to force fuel through the discharge valves, to be hereinaft r described, and through the fuel line H to the injector I ll. As soon as the piston 20 reaches a position in which the helical groove 22 communicates with the spill port l9. the pressure chamber 20a above the piston will immediately be relieved, and consequently the amount of fuel discharged from the pump under pressure may be adjusted by axially rotating the piston 20 to vary the point in its stroke at which communication of the groove 22 with the 'soillport l9 will be established.

"In the particular type of pump illustrated axial rotation of the piston 20 to adjust the capacity' of the pump is effected by means of a slidable rack 3| which engages a gear 32 carried' on the upper end of a rotatable sleeve 33 that surrounds the lower portion of the cylinder"barrel l1 and is provided with a slot 34 adaptedslidably to receive an upstanding fin- }35 which. constitutes an integral part of a collaij36 secured to 'the piston 20. The rotatable sleeve 33 jis retained in position within the bodyfM by engagement with the spring retainingwasher 26 and it will be apparent that endwisefmovementtof the rack 3| is effective through the'sleeve 33 and the finger 35 to cause axial rotation of the pis ton 26, the rack 3| preferably being provided with suitable calibrations, as shown, to indicate the adjustment of the piston in:.the cylinderbarrel. Fuelpumps of the type shown and thus liar-described are well known in the art and constitute no part of the present invention.

Mounted directly above the cylinder barrel H in the bore of the pump body I 4 is a suitable valve guide 31 adapted to be engaged and held in position by a sealing ring 38 which is in turn engaged by a retainer member 39 mounted within the bore of the pump body l4 and held in place by the cap member 40 secured to the pump body [4 by suitable cap screws 4|.

As shown in Figs. 2 and 3 a suitable valve member 42 is slidably disposed within the valve uide 31 and consists of a hollow valve stem provided at its upper end with a valve head 43 having formed therein a suitable valve seat 44 adapted to cooperate with the corresponding valve seat 45 formed on the upper end of the valve guide 31. As shown, the valve stem 42 is provided intermediate its ends with a plurality of axially extending passages 45 which communicate with a restricted chamber 41 surrounding the stem of the valve 42 immediately beneath the valve head 43. The valve head 43 which is in the form of a piston or plunger is provided with a suitable circumferential shoulder for receiving the lower end of a spring 48, the upper end of which engages a flange 49 on a valve stop member 50 which includes a hollow stem portion 5|, the lower end of which is disposed directly over the valve head 43 so as to limit the opening movement of the valve.

In this embodiment of the invention the head portion 43 of the valve member 42 is bored in alignment with the hollow stem portion to pro vide a valve guide for a second valve member 52 which comprises a hollow stem portion provided at its upper end with a valve head 53 having a seat portion 54 adapted to engage a correspondingly formed seat at the upper end of the bore in the valve head 43.

This second valve member is identical with the larger valve member 42 in which it is disposed, except for size, and is shown as provided with radially extending apertures 55 which communicate with a restricted circumferential chamber 56 disposed immediately beneath the valve head 53. Likewise, the valve head 53 is provided with a suitable circumferential shoulder for receiving the lower end of a spring 51, the upper end of which engages a flange on a valve stop member 58 having a hollow stem portion 59, the lower edge of which is disposed immediately above the valve'head 53' for limiting the opening movement of the smaller valve mem ber.

It will be observed that each of the valves 42 and 52 are arranged when open, to provide direct communication between the pressure chamber 20a above the piston 20 within the cylinder barrel l1, and a chamber 60 formed in the retainer member 39 within which the valve members and their respective springs and stop members are contained. As shown, the stop member 50 for the larger of the two valves is provided with axial passageways 6| which communicate the chamber 69 With the outlet passage 62 of the pump which outlet passages is adapted to be connected to the fuel line I l of Fig. 1. Likewise the stop member 59 is provided with axial passages 63 which communicate the chamber 60 with a longitudinal passage 64 which communicates with the outlet passage 62 through a similar longitudinal passage 65 in the stop member 50.

It will be understood that the valve members 42 and 52 are maintained closed by the springs arran e (iii-andISfIiduringethesuction. stroke otthermamp: I2 soas .toxprevent the return: of fuelcfnomztller fusll lin'eiv Ill". of the. injection: system illustrated:

in -Fig.1 1 As the iston. Z-Iisoff the pump: Ia movesi upwardly J at pressure; willihez. developed:

which: Will 51E817 cause; the valve. memberrrEZ. :to Y

up: the: valve=c52 will. open: widen. untilrthe' v upper endr of the valve headi Siengages: the vaive stop tli. Atilight loads, where: small amountszofzfuel: areibeingdelivered; the opening providedgby the valve 52': w-ill be': sufficient :to permit; the". passage: of all oil the fuel to:. the. pump) outlet iizzwithout: developing:sufficient.pressureitolcauseiopening19 hodiment; the springc'lflzomthe largerizvalyelflgisy 2O iii-1Y5;- I

the-larger valve dgiwhichi is maintained close by the spring 58;..thespring: icr-beingistronger thanthe; spring. 57.. As soon as the pressure within the pump chamber is relieved through the spill port. Ii-r asiheretofore described the spring; 51. will force. the .valve. 52. toclose and the design of the valve head 53 in.;coni11 nc,tion with the restricted chamber 56 andthe radial passages 55 provides a piston actionsuch' as to cause a predetermined amount ot-fuei to be withdrawn from .the'fluel line H into the chamber Silduring closing-movement of the valve; 3

At somewhat heavier loadsthe opening ofthe valve. Eli-will not be suificientto; accommodate all. of the; fueldelivered by thepump without building; up: a sufficiently highipressurei-to cause opening: movement of the lar i i'r VELIVQQQZ? and at-:maedmum: loads both ofthevalves will open tor-the;- meximum extent permitted by the. stop members: 5.9; and; 5 I The head 43-. on the larger valve 42 is likewise designed in conjunction with the restricted chamber 41 and the axial passageways 46 in the valve stem 42 to effect Withdrawal of a predetermined amount of fuel from the fuel line I I into the chamber 60 during closing movement of this valve and the respective proportions of the two valves are so chosen that the smaller valve 52 will effect a smaller amount of retraction or withdrawal of fuel than the larger valve 42. Thus, it will be seen that under light load conditions only the smaller valve will open and only a small amount of retraction will occur during closing of this valve, and that the retraction provided by the two valves together will increase in accordance with the amount of fuel delivered by the pump up to the maximum speed and load conditions under which both of the valves achieve their maximum opening and their maximum retraction.

In Fig. 4 another form of discharge valve means is illustrated for carrying out the presentinvention in which a pair of valves I0 and II are arranged in side-by-side relation rather thanbeing arranged one within the other as in the embodiment of Figs. 2 and 3. The valves I0 and II may be arranged within parallel bores in a single valve guide I2 so as to communicate with the pump space 2011 above the piston in the cylinder barrel I1 although it will be apparent that the valves may be arranged in individualvalve guides if desired. The valves I0 and II, which differ only in size, are provided with splined stem portions I2 and 13, respectively, with circumferential shoulders 13 and I4, respectively, and with suitable valve heads 15 and 16, respectively. As

suitable..litladine spring 'lllandiiwitlnaiwalve stop: 1. 3; which-zis suitablysboredl-andzapertureditoicomsmunicate with a..passagewayr119ileading Ian-the; pumpzoutleti; 8 correspondsirtoi the; outlet 62amtheaembodimentmfziligsa hand- 2.. Similarly; the. smallenvalive .I I: prdvidemwith. 351-118 117313 spring: 8. I.= and with: a: llailltfiastflpla2.WhlChflSibOI-fldl and: apertured" 5018's. to provide; communicatiom through;a:.passageway-"8-3s with the pumpizautiw The valves Ill and H individually are of a type: well known in the art and are designedzgt'mmrovid'e 1 a. determined; amoununf: retraction during closings movement: depending-"upon; the-.;inter;-:= relation. of" the valve; heads }andi.the.-..shoulders- 13;. andfle'i As inz tlia previously" described .ems

stiffer than; the: spring: .81; onwthe smaller: v II; and. consequent/1 1 the same inter-related p eratiorr. of: the: twea valves is; obtained-atoypnovide automaticivariati-onofitheaamountgofi retraction-i oniuel;withdrawalibetweeninjectionsiin alQQQId-r ance; with: the amount; of. fuel 1 delivered during; eaclrinfi .ectionip'eriodbytthepumpslm H In. the; embodiment I of the; inventiomshow-n ini E ia; p5.- er." dischar evalv s-m ans for: pr v di automatic; variation: in. the retraction oryfllelr withdrawal, in. accordance A withsthe amount. of. fuel;delivered:during injectionrbyythepump come priseszalsingle valve -84-mounteddn the bore-8d f. a suitable valves-guide. 8B- thelowemendlofg the bore (MK- communicating; with the pump chamber 2.8mand.being;adapted:tovreceive the stempore tion of valve; 86; which .;stem.--portiqn isprovided w thapl li .Q ve t ca lyl xte insi slots: N: t h osr r rdec e a nvde th from the: bottomof the valye stemqto, a-pointslightly below;- thepvalve headttg. The valve-head 83-, as -shown; i s provided-.1 with asuitablaspring; .8 fipwhich non mally maintains the valve closed and if desired a suitable stop (not shown) may be employed for limiting the opening movement of the valve. It will be understood that the chamber within which the spring 89 is disposed is in communication with the pump outlet and the fuel line I I and in this embodiment of the invention the degree of opening movement imparted to the valve 84 is dependent upon the amount of fluid delivered by the pump vand is controlled by the increasing depth of the slots 81. Likewise, because of the increasing depth of the slots 81, the amount of retraction provided by the valve head 88 during closing will be a function of the extent of the valve opening and thus a functionof the amount of fuel delivered by the pump. Consequently, less fuel will be withdrawn from the fuel line during closing movement of the valve 84 after a slight opening movement thereof on light load operation, than will be withdrawn during closing movement of the valve on heavier loads in which a greater opening movement of the valve is required.

It will thus be seen that in accordance with the present invention a fuel injection system is provided including discharge valve means wherein the amount of fuel withdrawn from the fuel line between injections is varied automatically in accordance with the amount of fuel supplied by the pump during the injection period, i. e., in accordance with the speed load requirements of the engine. It has been found that fuel injection systems embodying the present invention will provide satisfactory fuel injection over wide ranges of operation. for example, with fuel in- 7 Jections varying from a minimum-of 95 cu. mm.- to a maximum of 6000 cu. mm., without encountering objectionable secondary injection or dribbling at the injection nozzle.

While particular embodiments of this invention have been shown, it will be understood, of course, that the invention is not to be limited thereto, since many modifications may be made, and it is contemplated, therefore, by the appended claims, to cover any such modifications as fall within the true spirit and scope of this invention.

-Iclaim:

l. In a fuel injection system of the type including a pump adjustably operable to supply predetermined metered amounts of fuel under high pressure at each stroke and to release the high pressure abruptly upon delivery of said metered amounts, the combination of discharge valve means comprising a pair of valves connecting the high pressure side of said pump to the fuel line of said system, each of said valves including retraction means for withdrawing fuel from said fuel line during closing movement of said valves, stop members for limiting the opening movement of each of said valves, and individual spring means of difierent stiffness for resisting opening movement of said valves, whereby the opening of said valves and the amount of fuel withdrawn from said fuel line by said retraction means is dependent upon variations in the metered amounts of fuel supplied by said pump.

'2. In a fuel injection system of the type including a pump adjustably operable to supply predetermined metered amounts of fuel under high pressure at each stroke and to release the high pressure abruptly upon delivery of said metered amounts, the combination of discharge valve means connecting the high pressure side of said pump to the fuel line of said system and comprising a pair of valvesone of which opens under a lesser pressure than the other, each of said valves including retraction means for withdrawing a predetermined amount of fuel from said fuel line during closing movement thereof.

3. In a fuel injection system of the type includinga pump adjustably operable to supply predetermined metered amounts of fuel under high pressure at each stroke and to release the high pressure abruptly upon delivery of said metered amounts, the combination of discharge valve means comprising a first valve connecting the high pressure side of said pump to the fuel line of said system and including a valve member having a central passageway therethrough, and a second valve disposed in said passageway and including a second valve member, each of said valve members including retraction means for withdrawing fuel from said line during closing movement thereof, and individual spring means of different stiffness for effecting closing movement of said valve members.

ROBERT A. LASLEY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,999,693 Hill Apr. 30, 1935 2,019,103 Thege Oct. 29, 1935 2,090,351 Heinrich et al Aug. 17, 1937 2,131,779 Zwick Oct. 4, 1938 2,163,313 Volt June 20, 1939 2,178,902 Clausen Nov. 7, 1939 2,382,000 Bremser Aug. 14, 1945 2,407,610 Kammer Sept. 10, 1946 2,414,518 Garday Jan. 21, 1947 2,463,374 Garday Mar. 1, 1949 

